Enhanced GMI effect in tortuous-shaped Co-based amorphous ribbons coated with graphene

Enhanced giant magnetoimpedance (GMI) effect has been observed in micro-patterned Co-based Metglas 2705M amorphous magnetic ribbons coated with single-layer graphene. The micro-patterned ribbon was designed for tortuous structure and fabricated by MEMS technology, and the graphene thin film was developed by spin coating and dispensing method onto the surface of ribbon. Relative to the plain ribbon, at a measured frequency of 6 MHz and a field of 20 Oe, a 13.1 % enhancement of the maximum GMI effect was observed in the ribbon by spin coating graphene. However, there was a small change of the GMI effect in ribbon coated graphene by dispensing method. AFM observation confirmed a smoother ribbon surface by spin coating graphene. The very large enhancement of the GMI effect is a consequence of reducing the ribbon surface roughness and the closed magnetic flux path under the graphene thin film layer. This result provides a potential thinking for designing high sensitivity, lightweight and flexible GMI sensor with graphene-based materials.